I've never owned one of these before, but I've always been impressed by this combiner. I've heard that there are some differences between the Japanese and RID versions (and maybe the Korean Car Robots version too), but I don't know what they are.

I'm just curious to hear which version people think is better. Any known issues associated with either one?

the gun from railspike was modded when brought over to the USA, the tip was extended and rounded off. not much of a big deal except it no longer fits inbetween his legs in train mode. easy fix though a quick file down of the weapons tip makes it all better

Mine's a mix. I have Japanese Rail Spike but American Rapid Run and Midnight Express. They fit together fine, but I think Japanese Rail Spike has more clear parts (with a green tint) and he forms the head so if you only get one Japanese toy of the three go for Rail Spike (he's the indigo and white one). I'm not sure about Rapid Run and Midnight Express but it looks like in the American versions, clear windows might have been colored over with gray paint. The Japanese instructions are eaiser to follow too. More detailed pictures with more steps shown. Easily my favorite combiner too.

I absolutely love JRX; without a doubt my favorite combiner, period. Compared to Railracer, I vastly prefer the look of the clear plastic and the total lack of vehicle-mode Autobot insignia that was so rampant in RiD. However, one of the clear pieces that swivels out to change J-5's hips into JRX's shoulders has broken irreparably on mine. It still holds together, but it's wobbly and it just plain looks bad. I don't know if it's from material choice or what, but I figured I'd bring it up.

I'm against the grain on this one having seen the JRX up close for the first time over the weekend.

Yea, the clear windows are nice, but I find the painted clear plastic to look crummy from any angle but front on. Railracer just seems more solid especially the leg portions as you never catch a bad view where the paint ends.